Network services based on the Internet Protocol (IP) are today offered over several types of wireline and wireless network technologies. Internet Service Providers (ISPs) and network operators who own and handle several different types of access networks are starting to offer service bundles, such as General Packet Radio Service (GPRS) and Wireless Local Area Network (WLAN) access within the same subscription. Mobile end user devices that offer multiple access interfaces are also reality and are expected to become the norm (e.g. Personal Digital Assistants (PDAs) and laptops with GPRS, WLAN, Ethernet and Bluetooth).
Multi-access communication systems are in general more flexible than single-access networks but they also introduce an additional degree of complexity and involve a number of new requirements, choices and considerations. Thus, mechanisms that are capable of handling user traffic and packet flows in complex multi-access network in a satisfactory manner would be very desirable.
General aspects of multi-access are dealt with in the framework of the Always Best Connected (ABC) service [1], which envisions a communication environment where the user is always connected over the best available access network and device. Some important areas in this context are subscription handling and infrastructures for authentication/authorization; mobility management; and how to choose access including how to define “best”.
In a scenario where a user may have several options for IP network access, either through the same network service operator (ISP and/or mobile operator), or via multiple operators and subscriptions, a choice of access thus needs to be made. This choice can be based on different factors such as:                Access cost for the user        Performance requirements (due to type of application, device etc.)        Available access networks for the user (coverage, device, subscription profile etc.)        Network operator's preferences (load balancing, traffic priority etc.)        
In this context it is a challenge to balance factors like the above into an appropriate decision on what access network to choose.
In accordance with the International Patent Application WO 01/35585 A1 [2], the end device identifies available access networks and uses an indirect interface, such as a Bluetooth radio interface, to determine their respective access capability (cost of access, available bandwidth, etc.). The determined access capability is compared to a preferred access capability of the end device/user, which is stored at the end device and can be updated by the user. After all available access networks have been checked, a best access is selected. The end device may continue to look for new available access networks and reconsider its access decision during a connection.
U.S. Patent Application 2001/0141393 A1 [3] addresses situations where access to an IP-based communication network can be obtained via a plurality of bearers. In order to let applications and users benefit from the availability of several transport alternatives, [3] permits multiple packet flows to and from an application to utilize multiple accesses simultaneously. Hereby, different packet flows (e.g. video and audio media flows) of the same session, can use different access technologies depending on their respective characteristics. The mapping of flows onto the bearers is controlled by a link manager arranged in the user equipment. The link manager defines routing tables for the packet communication based on e.g. user or external preferences that can be stored in a policy database in the user equipment.
Conventional traffic handling mechanisms like the above-described solutions of [2], [3] are generally associated with rather heavy demands on both the end user and on his/her user equipment. The solutions are primarily focused on the best access seen from a user perspective, which may not always coincide with what is best for the overall traffic situation. Furthermore, very frequent updates of the prioritization list would be required in order to respond properly to changed conditions.
Accordingly, there is a considerable need for an improved method of handling traffic in communication systems associated with several access possibilities.